This invention relates to an endoscope having a flexible sheath and in particular an endoscope equipped with a film cassette disposed within the forward end section of a sheath insertible into a body cavity of a human being and having a roll of film on which any affected portion of the body cavity can be photographed.
A conventional endoscope such as a gastroscope, includes a photographing device such as a patrone, cartridge or cassette (hereinafter referred to merely as a cassette) within the forward end portion of a sheath, and a body cavity of a human being is photographed through a photographing window provided at the forward end portion of the sheath. A film is sequentially fed frame by frame, during the photographing, into the sheath by a manual operation at a control section of the endoscope. Upon completion of photographing, the sheath is withdrawn from the body cavity of a human being and a cap member is removed from the forward end section of the sheath and an exposed film is taken out, together with the cassette, from the forward end section of the sheath. Therefore, there is a fear that the exposed film will be impaired due to the exposure of a daylight. It is required that the exposed film be taken out at a dark room.
Furthermore, since the exposed film is sequentially withdrawn from the cassette into the sheath, a restriction is imposed on the inner diameter or size of the sheath. That is, the inner diameter of the sheath can not be made too small due to the width of the film. In view of a current requirement that the inner dimension of a sheath be made minimal to alleviate pains of a patient, a problem is posed here. If the width of a film is made narrower instead of increasing the width of the sheath, an observed area corresponding to any affected portion of the inner cavity of a patient is narrowed, making it impossible for the observer to clearly and fully observe the affected portion of the inner cavity. As the width of the film is made narrower, there is a fear that the film will be torn apart. For this reason, the sheath can not be bent to a greater extent and in this sense a restriction is made to the flexibility of the sheath.